docs: def _rewrite_geometry(geom, new_lines):
      """
      Re-encode a list of Lines with absolute MoveTos as a continuous stream of
      MVT geometry commands, each relative to the last. Replace geom with that
      stream.
      """
  
      new_geom = []
      x = 0
      y = 0
      for line in new_lines:
          moveto, endsat, lineto_cmds = line
  
          dx = moveto.x - x
          dy = moveto.y - y
          x = endsat.x
          y = endsat.y
  
          new_geom.append(9)  # move to, run_length = 1
          new_geom.append(zigzag(dx))
          new_geom.append(zigzag(dy))
          new_geom.extend(lineto_cmds)
  
      # write the lines back out to geom
      del geom[:]
      geom.extend(new_geom)